The "Rukl" numbers refer to charts in
Antonin Rukl's Atlas of the Moon, widely acclaimed by lunar observers as the best lunar atlas for the telescopic observer. Long out of print, the
second edition has been recently
reissued by Sky Publishing. The "L" numbers refer to the feature's position in the Lunar 100, where applicable. The Lunar 100 is an observing list covering the 100 most significant features on the Moon, ordered by difficulty.
Rukl 50, Libration chart VII. L 80. This feature on the extreme west limb is normally on the lunar far side. It is visible only on rare occasions when lunar "libration" brings it into view. Libration is sort of a "nodding" motion we see where the Moon tips one side a little bit toward us, then another. It is caused mainly by the Moon's non-circular orbit.
Copyright © 2003-2007 Michael Portuesi.
See the front page for licensing information.
Photo album generated by
album
from Dave's
MarginalHacks
on Sat Nov 8 19:35:56 2008
